SOOOO..since I had a good night of sleep to dream it over, I have recalculated my choice. Since my earlier premise was that someone was MAKING me chose, I chose a battle rifle or carbine.
Having thought about another scenario....that I have completely lost my marbles and CHOOSE to only have one gun (which in my mind is slipping into dotage and losing all heart to live) I would chose now to tell my older self to keep the Model 67 Winchester which started me on this journey at the beginning. It holds all of the joy and adventure of the early years and the unbending hope of better days and great fun to come. It is walnut and steel. It came from my Grandpa who was loathe to give it up, but did. It had a silver bolt, fired one shot, smelled of Hoppes and faintly of burnt powder. It was powerful...so powerful it could shoot 75 yards and hit a bottle. It was accurate...I know so because I could pull a stem of grass gone to seed, lean it against a sapling and at twenty feet offhand shoot the stem in half. It was quiet, as 22's go. It was maintained with love and oil, and a pocketful of lint covered 22 shells was enough to bring several days of stalking chipmunks, shooting acorns, sniping cans and hoping to save a few shells out so I could do it again, soon. It cleaned with an old rod and some t-shirt shards. A bit of floor wax on the walnut made it shine, and 3 in 1 on the barrel made the old bluing as pretty as any custom Purdy. When I carried it afield I was young and my daddy was alive, walking on his two wooden legs to make sure his son got to have adventure, despite the blisters walking caused him. I was full of hope, and the days ahead though unseen were looked forward to with anticipation unclouded by worry, death or the weight of life in a broken world. I would keep that old gun, and in my chair I would hold it and with eyes clouded with age I would be young again, holding my 22 in one hand, and with the other holding my daddy's hand looking forward to what was to come.
Yes, I would keep the Model 67.